The present disclosure relates to rocket engines, and more particularly to a gas generator system therefor.
Rocket engines utilize different types of rocket propellants. Liquid propellants are desirable as they generally provide a higher specific impulse than solid propellants. Among liquid propellants, hydrogen-oxygen propellants represent a benchmark for desirable specific impulse. However, there may be some operational drawbacks as liquid hydrogen is demanding in terms of storage, delivery, etc.
Kerosene is a suitable alternative to hydrogen as a rocket propellant, however, kerosene may be vulnerable to combustion efficiency and stability issues. Combustion efficiency generally refers to the completeness of the burning of propellants during engine operation. In kerosene-oxygen rocket engines, some kerosene may exit without being burned, which lowers combustion efficiency and engine thrust. Combustion stability may also be an issue with kerosene rocket propellants, in that oscillations in pressure may be produced.
Combustion instability is typically defined as combustion resultant pressures that vary more than +/−10% of the mean pressure which may occur from the hydraulic effects of the incoming propellants or from non-steady heat release from the combustion process. Combustion Instability may occur in any propellant class, however, the propellant combination that suffers the most is hydrocarbon (HC) fuels and liquid oxygen (Lox) oxidizer. The large HC molecule must be vaporized and then split into its constituents to combust. It is this process and its effect that may lead to combustion instability. Therefore fuel propellants that are often used in the industry such as RP-1 (C12H24) may be particularly problematic.